Metadata Report for BODC Series Reference Number 1364251


Metadata Summary

Data Description

Data Category Atmospheric composition
Instrument Type
NameCategories
PDZ Europa ANCA-GSL elemental analyzer  elemental analysers
PDZ Europa 20-20 isotope ratio mass spectrometer  mass spectrometers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Mingxi Yang
Originating Organization Plymouth Marine Laboratory
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier AMT22_ATM_OVOC_YANG_PML
BODC Series Reference 1364251
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2012-10-10 15:30
End Time (yyyy-mm-dd hh:mm) 2012-11-20 14:30
Nominal Cycle Interval 3600.0 seconds
 

Spatial Co-ordinates

Start Latitude 50.41060 N ( 50° 24.6' N )
End Latitude 46.52660 S ( 46° 31.6' S )
Start Longitude 2.46130 W ( 2° 27.7' W )
End Longitude 52.89010 W ( 52° 53.4' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth -18.0 m
Maximum Sensor Depth -18.0 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution Fixed common depth - All sensors are grouped effectively at the same depth which is effectively fixed for the duration of the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum -
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
ACYCAA01 1 Dimensionless Record_No Sequence number
ALATZZ01 1 Degrees Lat Latitude north
ALONZZ01 1 Degrees Lon Longitude east
MXRAAC01 1 Parts per billion AtmosAcetone Mixing ratio of acetone {propanone (CH3)2CO CAS 67-64-1} in the atmosphere by proton transfer reaction mass spectrometry
MXRAAH01 1 Parts per billion AtmosAcetaldehyde Mixing ratio of acetaldehyde {ethanal CH3CHO CAS 75-07-0} in the atmosphere by proton transfer reaction mass spectrometry
MXRAMT01 1 Parts per billion AtmosMethanol Mixing ratio of methanol {CH3OH CAS 67-56-1} in the atmosphere by proton transfer reaction mass spectrometry
 

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

Problem Reports

No Problem Report Found in the Database

RRS James Cook (JC079) AMT22 Atmospheric OVOC Mixing Data Quality Report

The data were quality controlled by the originator before being received by BODC and no further issues were identified with the final submitted dataset.


Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."


Narrative Documents

RRS James Cook (JC079) AMT22 Atmospheric OVOC Mixing Instrument Documentation

The following table shows the instrument used:

Instrument Model Serial Number Parameter measured
Ionicon High Sensitivity (HS) Proton transfer-reaction mass spectrometer n/a Atmospheric OVOC concentrations

RRS James Cook (JC079) AMT22 Atmospheric OVOC Mixing Ratios Data Processing Document

Data collection, measurements and originator's processing

Concentrations of atmospheric Oxygenated Volatile Organic Compounds (OVOCs) were quantified by a protontransfer-reaction mass spectrometer (PTR-MS) located in the meteorological lab. The PTRMS performed well during the cruise, with good sensitivity and without any notable issues, even in rough weather. For around 19 hours per day, the PTR-MS operated under atmospheric mode and continuously measured at ~2.1 Hz. Air was drawn in from the meteorological platform above the bow via ~25 m of quarter inch internal diameter PFA tubing by a vacuum pump. For most of the cruise, methanol, acetone, and acetaldehyde were measured simultaneously. Between 3 rd and 16 th November 2012, only methanol and acetone were measured because the level of acetaldehyde was near the instrument's detection limit. Dueterated methanol and acetone gas standards were injected continuously into the inlet line. The standard flow was regulated by a digital thermal mass flow controller. Ambient concentrations of those OVOCs were then calculated from the ratio of the natural and dueterated signals. The use of dueterated standards minimizes uncertainties due to instrumental drift and variable efficiencies. Background values were taken by directing ambient air through a catalytic converter, which removes organic compounds, for two minutes at the top of every hour. A plastic funnel, initially attached to the front of the inlet, was found to emit contaminants at the mass to charge ratios of acetaldehyde and acetone (m z -1 45 and 59 respectively). This contamination was most severe under direct sunlight and under high temperature. The funnel was removed on 29 th October 2012 and the problem disappeared thereafter. However, acetaldehyde and acetone air concentrations before 29 th October 2012 were highly uncertain. For that period, the daytime data were discarded, when the contamination was the most severe, and the nighttime data were corrected by detrending with temperature, methanol was unaffected. The hourly averaged concentrations are included here. To remove the influence of ship's exhaust, only the relative wind direction sector between -110° to +110° and relative wind speed over 2 m s -1 are retained. More information may be found in Yang et al., 2014.

BODC Data Processing

The data were submitted to BODC in teb-delimited text format consisting of Date and Time, Latitude, Longitude, Atmospheric methanol mixing ratio, Atmospheric acetaldehyde mixing ratio and Atmospheric acetone mixing ratio. The data were then transferred to the BODC format and loaded to the database. Parameter codes defined in the BODC parameter dictionary were assigned to the variable as shown in the table below:

Originator's Header Originator's Units Originator's Description BODC Parameter BODC Units BODC Description
lat n/a latitude ALATZZ01 Degrees Latitude north
lon n/a longitude ALONZZ01 Degrees Longitude
MeOH_ppb ppb Atmospheric methanol mixing ratio (parts per billion) MXRAMT01 Parts per billion Mixing ratio of methanol {CH3OH CAS 67-56-1} in the atmosphere by proton transfer reaction mass spectrometry
MeCHO_ppb ppb Atmospheric acetaldehyde mixing ratio (parts per billion) MXRAAH01 Parts per billion Mixing ratio of acetaldehyde {ethanal CH3CHO CAS 75-07-0} in the atmosphere by proton transfer reaction mass spectrometry
Acetone_ppb ppb Atmospheric acetone mixing ratio (parts per billion) MXRAAC01 Parts per billion Mixing ratio of acetone {propanone (CH3)2CO CAS 67-64-1} in the atmosphere by proton transfer reaction mass spectrometry

Screening

The data was csreened using the in-house software Edserplo. The data was considered to be of good quality and no additional flags were applied.

References

Yang, M., Beale, R., Liss, P., Johnson, M., Blomquist, B. and Nightingale, P. (2014). Air-sea fluxes of oxygenated volatile organic compounds across the Atlantic Ocean. 14, 8015-8061, doi:0.5194/acpd-14-8015-2014

PDZ Europa 20-20 isotope ratio mass spectrometer

The 20-20 isotope mass spectrometer brochure was not available however, based on evidence from other websites and the 20-22 mass spectrometer brochure the key features are very similar and are as follows:

120° extended geometry with an 11 cm radius magnetic sector giving an effective 21 cm radius dispersion and double direction focusing. Additional high dispersion long spur with 98.8° sector which creates a distance of 24 cm between the focal points for m/z 2 and 3. This leads to an abundance sensitivity at m/z 3 of <1 ppm which eliminates helium tailing in to the D/H collector.

Truly universal Faraday triple collectors for simultaneous collection of adjacent masses in the range 28,29,30 - 64,65,66 with no adjustment of collectors or amplifiers. Additional single Faraday collector and high gain amplifier for m/z 3 on the hydrogen spur.

The desired combination of the 4 collectors is selected through the software. Software switchable variable gain amplifiers and 50v amplifier outputs are available as options.

Optional extended geometry system to incorporate up to 12 collectors for custom applications.

Asymmetric extended geometry to give true stigmatic focussing with twice the dispersion of normal geometry with the same radius sector.

Shorter path length than traditional extended geometry to decrease ion/molecule interactions and so ensure 100% transmission through the analyser and a sensitivity which is higher than any other commercial IRMS (<1000 molecules/ion for CO 2 ).

Small analyser footprint and wide flat peak shape reduce the effect of temperature drift therefore removing the need for peak centring during analysis.

Design allows greater tolerance of the known variables of ion optics making the manufacture of the analyser more reproducible and less sensitive to magnet positioning.

True differential pumping by turbo-molecular pumps with a high compression ratio for both He and H2, to remove the detrimental effect of abundance sensitivity during continuous flow applications and eliminate memory.

With a mass range covering 2 to 96 AMU it is suitable for the analysis of light stable isotopes in all the commonly measured gases; H 2 , N 2 , NO, N 2 O, O 2 , CO, CO 2 , SO and SO 2 .

Triple port reference gas injection system. Suitable for calibrating each sample, using a reference gas instead of an internal standard and for easy tuning of the mass spectrometer. Size, type and positioning of reference gas pulses are under software control.

Data acquisition system uses state of the art highly stable and linear high frequency converters which produce integral slices with zero dead time and quantisation below the beam statistical noise floor at all signal levels.

The 20-22 isotope ratio mass spectrometer brochure may provide more information.

PDZ Europa ANCA GSL Sample Preparation Unit

The ANCA-GSL is a combined elemental analyser and gas purification module which produces clean gas samples for a 20-22 or GEO series isotope ratio mass spectrometer. The ANCA-GSL module allows samples such as soil, viscous liquids, plant material and organic compounds, to be analysed directly by utilizing Dumas combustion for 15 N, 13 C and 34 S or pyrolysis for 18 O and D. It also allows isotope analysis of abundant gases from septum sealed containers. During combustion mode, a capsule containing the sample falls into the combustion tube and is converted in the presence of oxygen to CO 2 , N 2 , NO x and H 2 O. An elemental copper stage reduces NO x , a MgClO 4 trap removes water vapour, a switchable Carbosorb trap can be used to remove CO 2 (for 15 N only analyses) and a GC column separates CO 2 from N 2 (allowing dual isotope analysis). Modified packings, a Nafion dryer and different GC column allow 34 S analysis. During pyrolysis mode, a capsule containing the sample falls into the pyrolysis tube containing glassy carbon grit. The pyrolysis products, CO, N 2 , and H 2 are purified by chemical processes. A MgClO 4 trap removes water vapour, a Carbosorb trap removes any CO 2 (minor by-product of the reaction) and a GC column separates CO from N 2 . The gas analysis facility of the ANCA-GSL is provided by an automated sampling needle and the gas chromatograph part of the module. N 2 , CO 2 and O 2 can be analysed at atmospheric concentrations while H 2 , SO 2 , N 2 O, CO 2 and NO can be measured at elevated levels e.g. from a head space, water equilibrations, continuous flow carbonate measurements and DIC analyses.

More information on the precision may be found in the ANCA GSL brochure .


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name JC079 (AMT22)
Departure Date 2012-10-10
Arrival Date 2012-11-24
Principal Scientist(s)Glen A Tarran (Plymouth Marine Laboratory)
Ship RRS James Cook

Complete Cruise Metadata Report is available here


Fixed Station Information


No Fixed Station Information held for the Series


BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain